pmopenlog(3) — Linux manual page


PMOPENLOG(3)              Library Functions Manual              PMOPENLOG(3)

NAME         top

       pmOpenLog - create a log file for diagnostics and debug output

C SYNOPSIS         top

       #include <pcp/pmapi.h>

       FILE *pmOpenLog(const char *progname, const char *logname,
               FILE *oldstream, int *status);

       cc ... -lpcp

DESCRIPTION         top

       pmOpenLog reassigns the standard I/O stream oldstream (normally
       stderr) to be associated with the file logname.  If logname is not
       "-" and already exists, it will be removed and recreated if possible
       (to ensure correct ownership and permissions from the caller to

       As a special case, if logname is "-" then no removal or reopening is
       performed and the function simply sets status to 1 and returns
       oldstream.  This is useful when the caller wants diagnostics on
       oldstream stream (normally stderr) rather than a file, e.g.  pmlogger
       -l- or pmcd -f -l-.  Logging to stderr is also useful for PMDAs in a
       containerized environment where it is beneficial for all PMDA logs to
       be written to pmcd's stderr stream (and thus to a single
       destination), whether that is a file such as pmcd.log or the original
       stream inherited from the shell.

       On return, the function value is the standard I/O stream, possibly
       replacing oldstream.  In the event of an error, the return value will
       be oldstream unchanged and status will be 0.

       For success, status is 1, and a standard preamble is written to
            Log for progname on hostname started date and time
       and an atexit(3) handler is installed to write the postscript message
       to logname
            Log finished date and time
       when the processes exits.

       progname is only used to annotate messages.

SEE ALSO         top

       atexit(3) and freopen(3).

COLOPHON         top

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Performance Co-Pilot                 PCP                        PMOPENLOG(3)